We just purchased an Arlo Pro 4 4-pack last week and an Arlo Audio Doorbell. We installed the system over the weekend and have been testing everything since then. We too have a very low speaker volume on the doorbell; it is hard to talk to anyone at the door. Also, the microphone volume seems very low - the 'guests' voice over the phone is very low, even at maximum volume. I agree - this needs to be fixed or it's going back to the store soon. That would be unfortunate because we like that it is very responsive - we get a call within a few seconds of pushing the doorbell button.
I pulled the box out of the trash so I can return it. The speaker volume on the Arlo pro cameras are just as unusable. Glad I got those from Costco so I can easily return the cameras too. Very dissatisfied.
Best Buy rep said a lot of people are returning these. No surprise.